FIELD OF THE INVENTION
This invention relates to a process for preparing a relatively dry crystalline product generally known as hemipotassium phosphate and to its utility as a acidulant generally useful in beverage formulations, both dry and liquid forms.
Orthophosphates have been known as ingredients in beverages for various purposes. Potassium levels have been found to be depleted in the body along with other salts and minerals through physical activity and beverages have been designed to replenish body fluids, ions, electrolytes and minerals lost thereby. A typical beverage mix to replenish as well as diminish loss of such elements by dehydration is disclosed in British Patent 1,252,781 to Bradley et al. In the beverage mixes mono- and dibasic potassium phosphates are employed in a dry mix which, when combined with water and other elements provide relief from water loss and its concomitant imbalance of salts and minerals in the body.
Generally phosphoric acid is employed as an acidulant and/or flavoring additive in flavored beverages such as colas, root beers, etc. However, phosphoric acid is generally available in liquid form only. One attempt to apply dry beverage mixes in which phosphoric acid is employed is found in U.S. Pat. No. 3,966,994 to Kennedy. This patent discloses a liquid beverage mix in which phosphoric acid is employed as an acidulant. Monoalkali orthophosphates are added to the liquid concentrate in at least equimolar amounts with respect to the phosphoric acid acidulant in the concentrate before drying. Both sodium and potassium orthophosphates are disclosed. According to Kennedy, it is unclear as to the final composition of the dried mix with respect to the form of phosphate acidulant in the dry mix. Kennedy expresses some degree of doubt as to the exact form of the phosphates employed in his dry mix, distinguishing it from the disclosure of U.S. Pat. No. 2,851,360 to Diller wherein partial replacement of the common acidulant, citric acid, by hemisodium phosphate is said to have advantages over the use of citric acid alone. However in Diller's U.S. Pat. No. 3,851,359 there is disclosure indicating that a complex is formed which is different than the hemiphosphate which may be expected from the combination of equimolar addition of mono potassium orthophosphate to phosphoric acid.
A large amount of potassium phosphate is employed in the fertilizer industry. Since both potassium and phosphorus are plant nutrients their combination into one compound provides an ideal product for such use. There is described in U.S. Pat. No. 5,112,460 a process for preparing alkali metal phosphates, including potassium and sodium alkali metals, by ion exchange of potassium chloride, hydrogen chloride and phosphoric acid. An air stream is employed to remove hydrogen chloride gas at temperatures below 200.degree. C. followed by steam stripping to produce an alkali metal orthophosphate.
Many beverage products contain an acidulant to compliment other flavorings or to either highlight or suppress other aroma components. Acidulants are added to beverages, especially nonalcoholic soft drinks and fruit products. Orthophosphoric acid and citric acid are widely used as well as other organic acids such as acetic acid, adipic acid, tartaric acid, lactic acid, malic acid, succinic acid and fumaric acid.
There is no commercial source of a dry, nonhygroscopic, inorganic acidulant for use in beverages, particularly dry mixes, which would effectively replace organic acids. A dry source of phosphoric acid acidulant would enable more convenient formulating as well as shipping, storage and handling of the most popular inorganic acidulant.